One multiplexing format established by MPEG 2 (Moving Picture Experts Group phase 2) is a transport stream. In transport streams, PESs (Packetized Elementary Streams) that are video and audio to be transmitted (elementary streams) which have been divided into portions of a predetermined size and packetized, and control information, etc. (hereinafter referred to as “section data”) for decoding elementary streams are divided into fixed length packets called transport packets (hereinafter called “TS packets”) and transmitted. Note that packet identifiers (hereinafter referred to as “PIDs”) that can identify a type of data included in a payload are included in the headers of these TS packets.
A data transfer apparatus is known that, in order to obtain, as necessary, such PESs and section data that have been divided into TS packets and transmitted, sequentially receives the transmitted TS packets and transfers the received TS packets to a memory area in accordance with the type of received TS packet.
The following describes this conventional data transfer apparatus.
FIG. 19 is a block diagram showing a structure of a conventional data transfer apparatus 5.
As shown in FIG. 19, the data transfer apparatus 5 includes a reception unit 1, a PID filter 2, a section filter 3, and an output unit 4.
The reception unit 1 transfers the received TS packets to the PID filter 2. In accordance with a PID set by a control unit (not depicted), the PID filter 2 extracts a TS packet that includes divided data of a necessary PES (hereinafter referred to simply as a “PES TS packet”), and transmits the extracted PES TS packet to the output unit 4. The PID filter 2 also extracts a TS packet including divided data of necessary section data (hereinafter, referred to simply as a “section data TS packet”) and transmits the extracted section data TS packet to the section filter 3.
The section filter 3 transmits, to the output unit 4, data of the payload of a transmitted TS packet from which unnecessary data such as stuffing bytes have been removed (hereinafter, the data as a whole is referred to simply as a “packet”, and data of the payload of a TS packet from which unnecessary data such as stuffing bytes have been removed is referred to as “valid data”). The output unit 4 burst transfers, that is, transfers as a group, the payloads of TS packets transmitted from the PID filter 2 and valid data of packets transmitted from the section filter 3 to separate areas in the memory 6 according to the respective PIDS. That is to say, the output unit 4 burst transfers each of the TS packets received by the reception unit 1 to the memory 6 as one unit.
Note that technology for extracting predetermined PESs and section data pieces with use of a PID filter and a section filter, as in the data transfer apparatus 5, is disclosed in patent document 1, for example.
Patent document 1: Japanese Patent Application Publication No. 2001-257716